Lately my w124 300D 2.5L has been shutting down slower and slower. Once I turn the key to off it takes 1 to 2 seconds for the engine to slow down and stop.

My first thought was that the shutoff actuator is going bad.

The first step I did was to remove the brown vacuum line from the actuator and the other end from the brake booster line. When I plug up the end to the actuator and use my MityVac on the other the line holds vacuum great with no bleed down. I believe this means the circuit from the brake booster line to the actuator is tight.

When I put the MityVac directly to the shut off actuator I can pump and pump the MityVac and the shutoff lever just moves down a bit and comes right back up to the no vacuum position.

When I push the shutoff lever to OFF and plug the shutoff actuator outlet the lever will slowly move up to the ON position.

I assume the actuator should hold a vacuum, correct? This must mean I have a leak in my actuator diaphragm.

I’ve seen the DieselGiant page about changing the actuator on what I think is a 123. Is there a good description somewhere about changing it on a 124?

I understand that if you put it in backwards you can mess up the engine.

This thread describes pretty well the physical location of the actuator. '92 2.5 Turbo: Replacing Vacuum Valve on Injector Pump

Thanks-Brad

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1993 W124 300D 2.5L Turbo, OM602.962
2000 Chevrolet Cavalier, 2.4L DOHC
2002 Ford Explorer, 4.0L SOHC
2005 Toyota Prius, 1.5L

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